We won’t truly know the long term effects until someone does a study on this. Theoretically and logically, as you say, this makes a lot of sense, but I have qualms about this thing too. Not that I don’t believe it, I sure do, and am happy that I will have my 20/20 vision back in about a year and a half.
We need definite studies that would start following people with various degrees of myopia before starting improving their vision and follow them all the way until they get to 20/20. Then the study should have a control group with corresponding degrees of myopia who should be followed for many years as well. Both groups of people should be followed basically until their deaths in order to determine what complications related to eyesight they develop and if there is a statistically significant difference between the two groups. Both the study group and the control group should be standardized according to multiple variables such as age, degree of refractive error, and possibly even motivational level to stick with improving vision for many years, and maybe some others too. During the study, various eye measurements, such as the axial length of the eye, should be repeated multiple times to track their progression as well.
I doubt we’re going to see anything similar in quite a while. Jake mentioned somewhere that he had a bunch of data accumulated over the years from his students, but I don’t know without having seen it what it is and if it’s valid enough to do anything scientific with it.
In the grand scheme of things, we improve our vision using objectively better vision habits. There’s not much else we can do to decrease our risk of eye complications apart from having good vision habits, a good diet, and managing medical conditions that are known to result in visual complications (e.g., diabetes mellitus, arterial hypertension, atherosclerosis, etc.)